Sieving method to isolate and detect teliospores of Tilletia indica in grain samples
A method was developed in the USA to isolate teliospores of Tilletia indica (EPPO A1 quarantine pest) from infested wheat grain samples. Samples of 50 g are washed through 2 sieves (nylon screens) of 53 µm and 20 µm pore size in order to remove debris, and to concentrate and isolate teliospores. The material retained in the 20 µm pore size sieve is suspended and centrifuged. Then, it can be directly observed under the microscope (it is noted that the presence of debris is greatly reduced) or plated onto agar medium for teliospore germination followed by PCR assay. It was concluded that this method is reliable and much faster than the standard centrifuge seed wash method. In particular, it is now used by USDA and Agriculture Canada as their official protocol for detection of T. indica in grain samples.
Sources
Peterson, G.L.; Bonde, M.R.; Phillips, J.G. (2000) Size-selective sieving for detection teliospores of Tilletia indica in wheat seed samples.
Plant Disease, 84(9), 999-1007.